Re: [PATCH v2 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

From: Uwe Kleine-König
Date: Tue Feb 20 2024 - 05:48:32 EST

Hello,

On Mon, Feb 12, 2024 at 08:17:29PM +0800, Jingbao Qiu wrote:
> Implement the PWM driver for CV1800.
>
> Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@xxxxxxxxx>
> ---
> drivers/pwm/Kconfig | 10 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-cv1800.c | 248 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 259 insertions(+)
> create mode 100644 drivers/pwm/pwm-cv1800.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 4b956d661755..455f07af94f7 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -186,6 +186,16 @@ config PWM_CROS_EC
> PWM driver for exposing a PWM attached to the ChromeOS Embedded
> Controller.
>
> +config PWM_CV1800
> + tristate "Sophgo CV1800 PWM driver"
> + depends on ARCH_SOPHGO || COMPILE_TEST
> + help
> + Generic PWM framework driver for the Sophgo CV1800 series
> + SoCs.
> +
> + To compile this driver as a module, build the dependecies
> + as modules, this will be called pwm-cv1800.
> +
> config PWM_DWC_CORE
> tristate
> depends on HAS_IOMEM
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index c5ec9e168ee7..6c3c4a07a316 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_PWM_CLK) += pwm-clk.o
> obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
> obj-$(CONFIG_PWM_CRC) += pwm-crc.o
> obj-$(CONFIG_PWM_CROS_EC) += pwm-cros-ec.o
> +obj-$(CONFIG_PWM_CV1800) += pwm-cv1800.o
> obj-$(CONFIG_PWM_DWC_CORE) += pwm-dwc-core.o
> obj-$(CONFIG_PWM_DWC) += pwm-dwc.o
> obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o
> diff --git a/drivers/pwm/pwm-cv1800.c b/drivers/pwm/pwm-cv1800.c
> new file mode 100644
> index 000000000000..3d7f2ff3a6c2
> --- /dev/null
> +++ b/drivers/pwm/pwm-cv1800.c
> @@ -0,0 +1,248 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * pwm-cv1800.c: PWM driver for Sophgo cv1800
> + *
> + * Author: Jingbao Qiu <qiujingbao.dlmu@xxxxxxxxx>
> + *
> + * Limitations:
> + * - It output low when PWM channel disabled.
> + * - This pwm device supports dynamic loading of PWM parameters. When PWMSTART
> + * is written from 0 to 1, the register value (HLPERIODn, PERIODn) will be
> + * temporarily stored inside the PWM. If you want to dynamically change the
> + * waveform during PWM output, after writing the new value to HLPERIODn and
> + * PERIODn, write 1 and then 0 to PWMUPDATE[n] to make the new value effective.
> + * - Supports up to Rate/2 output, and the lowest is about Rate/(2^30-1).
> + * - By setting HLPERIODn to 0, can produce 100% duty cycle.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +
> +#define PWM_CV1800_HLPERIOD_BASE 0x00
> +#define PWM_CV1800_PERIOD_BASE 0x04
> +#define PWM_CV1800_PWM_CV1800_POLARITY 0x40
> +#define PWM_CV1800_START 0x44
> +#define PWM_CV1800_DONE 0x48
> +#define PWM_CV1800_UPDATE 0x4c
> +#define PWM_CV1800_OE 0xd0
> +#define PWM_CV1800_HLPERIOD_SHIFT 0x08
> +#define PWM_CV1800_PERIOD_SHIFT 0x08
> +
> +#define PWM_CV1800_HLPERIOD(n) \
> + (PWM_CV1800_HLPERIOD_BASE + ((n) * PWM_CV1800_HLPERIOD_SHIFT))
> +#define PWM_CV1800_PERIOD(n) \
> + (PWM_CV1800_PERIOD_BASE + ((n) * PWM_CV1800_PERIOD_SHIFT))

I would have used a plain 0x08 instead of PWM_CV1800_HLPERIOD_SHIFT and
PWM_CV1800_PERIOD_SHIFT.

> +#define PWM_CV1800_UPDATE_MASK(n) (BIT(0) << (n))
> +#define PWM_CV1800_OE_MASK(n) (BIT(0) << (n))
> +#define PWM_CV1800_START_MASK(n) (BIT(0) << (n))
> +
> +#define PWM_CV1800_MAXPERIOD (BIT(30) - 1)
> +#define PWM_CV1800_MINPERIOD BIT(1)
> +#define PWM_CV1800_MINHLPERIOD BIT(0)
> +#define PWM_CV1800_PERIOD_RESET BIT(1)
> +#define PWM_CV1800_HLPERIOD_RESET BIT(0)
> +#define PWM_CV1800_REG_DISABLE 0x0U
> +#define PWM_CV1800_REG_ENABLE(n) (BIT(0) << (n))
> +
> +struct cv1800_pwm {
> + struct pwm_chip chip;
> + struct regmap *map;
> + struct clk *clk;
> + unsigned long clk_rate;
> +};
> +
> +static const struct regmap_config cv1800_pwm_regmap_config = {
> + .reg_bits = 32,
> + .val_bits = 32,
> + .reg_stride = 4,
> +};
> +
> +static inline struct cv1800_pwm *to_cv1800_pwm_dev(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct cv1800_pwm, chip);

Please rework the driver to use pwmchip_alloc(). See
https://lore.kernel.org/linux-pwm/a37a167364366b6cbe2dd299dce02731706213b2.1707900770.git.u.kleine-koenig@xxxxxxxxxxxxxx/T/#u
for a simple example for such a rework.

> +}
> +
> +static int cv1800_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm,
> + bool enable)
> +{
> + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> + u32 pwm_enable;
> +
> + regmap_read(priv->map, PWM_CV1800_START, &pwm_enable);
> + pwm_enable &= PWM_CV1800_START_MASK(pwm->hwpwm);
> +
> + /*
> + * If the parameters are changed during runtime, Register needs
> + * to be updated to take effect.
> + */
> + if (pwm_enable && enable) {
> + regmap_update_bits(priv->map, PWM_CV1800_UPDATE,
> + PWM_CV1800_UPDATE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> + regmap_update_bits(priv->map, PWM_CV1800_UPDATE,
> + PWM_CV1800_UPDATE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_DISABLE);
> + } else if (!pwm_enable && enable) {
> + regmap_update_bits(priv->map, PWM_CV1800_OE,
> + PWM_CV1800_OE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> + regmap_update_bits(priv->map, PWM_CV1800_START,
> + PWM_CV1800_START_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> + } else if (pwm_enable && !enable) {
> + regmap_update_bits(priv->map, PWM_CV1800_OE,
> + PWM_CV1800_OE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_DISABLE);
> + regmap_update_bits(priv->map, PWM_CV1800_START,
> + PWM_CV1800_START_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_DISABLE);
> + }
> +
> + return 0;
> +}
> +
> +static int cv1800_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> + u32 period_val, hlperiod_val;
> + u64 tem;
> +
> + if (state->polarity != PWM_POLARITY_NORMAL)
> + return -EINVAL;
> +
> + tem = mul_u64_u64_div_u64(state->period, priv->clk_rate, NSEC_PER_SEC);
> + if (tem > PWM_CV1800_MAXPERIOD || tem < PWM_CV1800_MINPERIOD)
> + return -EINVAL;

Please use:

if (tem < PWM_CV1800_MINPERIOD)
return -EINVAL
if (tem > PWM_CV1800_MAXPERIOD)
tem = PWM_CV1800_MAXPERIOD;

> + period_val = (u32)tem;
> +
> + tem = mul_u64_u64_div_u64(state->period - state->duty_cycle,
> + priv->clk_rate, NSEC_PER_SEC);

Given that you're supposed to configure the biggest duty_cycle not
bigger than the requested value, you have to round up here.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |

Attachment: signature.asc
Description: PGP signature